Residual stress in lithium niobate film layer of LNOI/Si hybridwafer fabricated using low-temperature bonding method

Ryo Takigawa, Toru Tomimatsu, Eiji Higurashi, Tanemasa Asano

Research output: Contribution to journalArticle

Abstract

This paper focuses on the residual stress in a lithium niobate (LN) film layer of a LN-on-insulator (LNOI)/Si hybrid wafer. This stress originates from a large mismatch between the thermal expansion coefficients of the layers. A modified surface-activated bonding method achieved fabrication of a thin-film LNOI/Si hybrid wafer. This low-temperature bonding method at 100 °C showed a strong bond between the LN and SiO 2 layers, which is sufficient to withstand the wafer thinning to a LN thickness of approximately 5 μm using conventional mechanical polishing. Using micro-Raman spectroscopy, the residual stress in the bonded LN film in this trilayered (LN/SiO 2 /Si) structure was investigated. The measured residual tensile stress in the LN film layer was approximately 155 MPa, which was similar to the value calculated by stress analysis. This study will be useful for the development of various hetero-integrated LN micro-devices, including silicon-based, LNOI-integrated photonic devices.

Original languageEnglish
Article number136
JournalMicromachines
Volume10
Issue number2
DOIs
Publication statusPublished - Feb 18 2019

Fingerprint

Residual stresses
Lithium
Temperature
Photonic devices
Polishing
Stress analysis
Tensile stress
Thermal expansion
Raman spectroscopy
Fabrication
Thin films
Silicon

All Science Journal Classification (ASJC) codes

  • Control and Systems Engineering
  • Mechanical Engineering
  • Electrical and Electronic Engineering

Cite this

Residual stress in lithium niobate film layer of LNOI/Si hybridwafer fabricated using low-temperature bonding method. / Takigawa, Ryo; Tomimatsu, Toru; Higurashi, Eiji; Asano, Tanemasa.

In: Micromachines, Vol. 10, No. 2, 136, 18.02.2019.

Research output: Contribution to journalArticle

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